Monorail tractor



Feb. 5,1946. G GOGA 2,394,168

MONORAIL TRACTOR A I Filed Feb. 26, 1943 2 Sheets-Sheet 1 4 INVENTOR IATTORNEYS Ges'Yoyfyq a Patented Feb. 5, 1946 UNITED STATES PA-TEN O'FF'IC'EJ MONORAIL TRACTOR- GeorgeFi Goga, Kenmore, N-l

Allplicationfebruary 26, 1943', ;Seria1';NQ.-17-f7;28?7- 13' Claims.

This invention: relates to. improvements; in tractors of the kindemployed in connection with overheadimonoraill carrier: systems;

Oneobj ectofthe invention is to provide-atractor which is so designedthat the required traction is .ohtainedzr independently of the weightstructed that wearing ofr'its wheels and wearing and-*peening: of theload supporting flanges of 'such shapes will beminimized.

A still i further :object iisr 'to" provide ;a tractor which, withoutsubjecting. :such sections? ofrthe supporting rail to StIGSSBSiOf anysubstantial magnitude, will negotiate switch crossingsand'itransfer'junctions. I

A stillfurther object is aatractor'whereinl-vprovisionismadei'forobtaining withfacility a :wide

range of speeds 'forleach speedz'of therparticular motor-by whichithetractor may-fbepowered.

A still further :objectistto provide a tractor which" is adaptedfor:high :speed travel andi rapid acceleration" :and: deceleration; thisobject contemplating: a tractor. which is so balanced and which isdriven insucha manner that swayingof the tractor; with attendantflexing;stressing,. and wearing down of" tthedoadesupporting :rai1,;is

: avoided.

Astillifurther objectiisza tractor wherein provision-:is madeion-obtaining the lrequired"traction -in-such a manner :that standardzpneumatic :tires may be employed .in cconnection with '1 the drivewheels-without' the hazard of such ttires heing subjected lto- :forces'.of :avma'gnitu'de -.-to be :de-

- structive;

A still further object istoprovidea novel construction and arrangementof the partsiofthe 1 tractor, whereby f to enable ther latter to'bezinstalled-with facility andito obtain: simplicity-and compactness indesign;

The invention isiillustrated .i-n the accom-panying-drawings-inwhich:

"Figure J 1 i is a side 1 elevational' view of! a tractor embodying-'thefeaturesof the in-vention;

Figure-2 is an end elevation;

"Figure -3 is an enlarged vertical section? taken Figure 4 is a top viewof the tractor; the:supporting; rail, to the extent that it 1 isindicated,

'being in section.

Eigurerfi'is. an: enlargedsection taken along-line tfiifi-i-lofiEigrures l.

Eigurecisa detail section taken along ine 5- -6 ,ofi'Ffigure :5.

Figure: .7 isltaidetailazsection taken al n lin ##lof Figure-6a Figure:8 .issafragmentarysectmn takenalong ilin'e iii-:8 lofi'Ei u fiThem-actor :is so designed that the; suspended .railL-whichui'szemployed: asiits track may be a standard structural shape, the rail IDwith which :the tEECtDIFiSZShDWn beingagconventional'Ieheam hayingupper?andizlower'iflanges :IEI and: |-,2;, -r e- .spectivelyaandiaxweb:13: ASIillUStilltld; the trac- Fmnincmdeaaframee lmhaving-zalfrontendextensionzil'fi, 85:1631L8Ild'Z-EX138I1S'101'1 h'i :and a body.secition :l 1, ttherendr extensions rheingrlocated along a=media-n11ine; extendingflongitudinally of the irame andlbeing:elevated-with respeot'ato rthe vhodysecetion randitheereantendzextension .being adapted to the" coupled in any-suitablemanner to the:load 'lr fiaz Thelfrontiend' extension! 5 is-suspended -below therailz-flli'byzastrolley.i8, being located'betweenidepending;spacedeapart arms ill ofthe trolley -.andibeingspivotallylconnectedztothelatter I Qi'carry, horizontal,tinwardlysdirected'sshafts 2|.

'Whe'elsrfl 2' onthet-latter--overlie an'di-ride upon the fiange lzr ofthe.-rail,' jthe said wheels preferably being: :mounted so: that theywill i-ride along ;the fiange' substantiallyi midway 'Pbetween the mar-:ginal edges ofitlie lattertandzthe web -t3. Preferably the 'wheelsi22='are guidedalong the flange by opposite]yilocatedzpairs of rollers. '23which engage the opposite sides or edges of theiraiLveach-pairiof:rollersibeingcarriedz'bya'yoke 2.4 which is :suitably Isecured'zto ethe adjacent trolley am I 9 and' -bein'g springeloadedz ifdesired. The rear :endextensiomlB of thesframe r l 4 issuspended belowthe .railzwt by armsQi-the upper. ends-0f which carryrin-wardly directedshafts 2B. Wheelsfl on sthe: latter overlie :and ride upon the':1o,wersfi'ange of theerail, preferably trackingawith :ithe :Wheelsofitheitrolleyilll;

"Theiwheels 22 andtZ'l-serve onlylfito support-the tractorr-ongtherails! ll. They: doenot norare' they intended-ate; guide it in {11381movement along the rail. iFla-ngeless .,wheels':= may, -t heref;or e,bevem- :ployed i and as such ::wheels 7 may the t-metmli d ,so

0 ithat theyvtravelralong;pathsspacedinwardlywith respectto the:marginaledges of the lowerlfla-nge they do: n'otiwearior peemoverxsuchedges: Nor :are theytthemselvessubjected tothe wearinaa i-tio'mofl such?edges. Theuse of special structural shapes or reinforcing of thelowergfflangerofrthe rail, as is the practice when flanged supportingwheels are employed and when the load carrying wheels are driven, isthus avoided.

The tractor is powered by an electric motor 28 which is mounted upon theunderside of the body section of the frame l4, collector arms 28a whichare carried by the said frame having sliding contact with conductor bars28b carried by the rail l8. A housing 29 on one end of the motoraccommodates-a worm: wheel which meshes with'and which is driven by aworm 3| on the rotor shaft of the motor, the worm wheel being fixed tothe lower end of a drive shaft 32. A coupling 33 connects the upper endofthe latter to a shaft 34 to which upper and lower gears 35 and 36,respectively, are fixed, the gear 36 meshing with a gear 31 which isfixed to a countershaft 38. Bearings 39 for the shaft 34 are mountedwithin upper and lower hubs 40 formed, or provided, upon a sectionalgear housing 4|, the said hubs being .journaled in the -14 in thevicinity of the end extension 15. The

sleeves 42 of upper and lowerbearings 43 carried by .across-frameM-which is mounted on the upper side of the body section ofthe frame bearings 45 for the countershaft 38am mounted in upper andlower hubs 46 formed, or provided,

upon a sectional gear housing 41, the said hubs r. being journaled insleeves 48 of upper and lower 1 bearings 49 which are carried bythecross-frame 44. I Thegear 31 (Figure 5) meshes with an idler gear- 50which in turn meshes with a gear 5|, the latter being fixed to the lowerend of a shaft 52"which carries a drive-wheel 53.

The upper end of the shaft 52 is journaled in an outboard bearing 54which iscarried by a frame 55, the

latter-being ibolted or otherwise secured upon a boss 56 formed upon thehousing 41. The boss -5$also accommodates abearing56a for the lower---end of theushaft 52'; The gear 35 meshes with an idler gear 51v(Figure 5). which in turn meshes with a gear 58. The latter is fixed tothe lower :end of a shaft 59 (Figure 4) which carries a drive wheelfifl,the upper end of the said shaft' being mounted in an outboard bearing ina frame 6| and'the lower end being mounted in. a bear- .ing in thehousing 4| as described in connection with the shaft 52. The wheels 53and 6B, which are driven by the two gear trains, engage opposite sidesof'the web l3 of therail and are driven inppposite directions to propelthe tractor along ithezrail Hi, the web engaging portions ofrthe wheelspreferably being provided bypneumatic tires GZ... ,7

.It will be noted that the housings u. and 41,

each of which carries one of. the drive wheels 1 53 and 60: and the geartrainlfor transmitting power to such wheel, are each mounted as a unitfor pivotal movement about a vertical axis which is coincident with theaxis of the shaft of the -.driving gear of the gear train, the housing4| .being'adjustable about anaxis coincident with the axis of the shaft34 and .the housing 41 being adjustable about an axis coincident withthe axis of the shaft 38.. Such angular adjust- "ments, therefore, maybe made freely and to any desired degree without necessitatingcorrections to be'made in the gears of either train. In other words thedriving relation of the gears in each train remains constant despiteadjustments of the housings 4| and41 and despite the fact i that as aresult of such adjustments one train l of gears may be moved asaunittoward. or. away from the other. i

-or to permit it to moveaway from; the web of the rail ID. The saidelements may be suitably locked in any adjusted positions of thehousings.

In this connection it will be noted that the tires of the two drivewheels always engage the web of the rail with equal pressure and thatany adjustments of one of the elements 64 automatically effects bothwheels in the same degree, the adjustment of such element moving theassociated housing in one direction while the resistance offered by therailto such movement is transmitted to the frame |4' so that the lattersimultaneously urges the opposite-housing in the opposite direction.Traction between the drive wheels of the. tractor and theweb of the raildoes not,

. therefore, depend upon-the weight of the tractor and may bepredetermined with respect to the load to be drawn and without addingsubstantially to such load or to the load upon the wheels which ridealong the lower flange of the rail. Wearing and deforming of the wheelsand rail flange are thus reduced to a minimum.

It will be noted that the drive wheels 53 and 60 are in the same planeas the rail l0 and turn in the same plane. The headroom required is thusreduced to a minimum and compactness and simplicity in design areachieved. Moreover, this enables the motor to be mounted under the framein such a position that the center of gravity of the tractor will belocated directly below the rail so that the weight of the tractor willtend to cause. it to assume and maintain a position in which the loadcarrying wheels and drive wheels cooperate properly with the rail. Afurther advantage achieved as a result of obtaining the desired tractionwithout the aid of the'load carrying wheels is that the necessity for 4any particular spatial relation between the axes of these wheels and thedrive wheels is avoided,

the'size and location of the latter being predetermined without regardto the location of the axes of the load carrying wheels.

The invention contemplates the removal of the idler gears 50 and 51 andthe gears 5| and 58 and the substitution for such gears of other gearsof different ratios'in order to enable various tractor speeds to beobtained with respect to a particular motor speed. To this end the topand bottom walls of each housing 4| and 41 are formed with elongatedslots 69 and 10 (Figures 5 and 6) for accommodating the ends of theshafts 1| which 69 and HI.

In connection with the foregoing it will be noted, referringparticularly to Figure 5,-that the immerses; rtita'ns'r'nitting bowermine d wheels; "1' ha's'the'a'dvaht'agethat'the ge "6r s eeds amen canhefoijtained' b3! va i itifiejatiosjd fth' idieigears sniahqsia thesrsna '58 ch they drive i's'subst'antlally ed as it enables "theiis'eof. ea;rs of a size wh1ch, if'the we tiain's bi 'j jupia'we; sam nesM51116 be iiii jssibl'e. Iii other wor' s the planar Ioca'ti6n's 6f thethe gear 'tra n'g 'diife'rent, a, p r'i rc'ivi's'i'on is madewheiteby Whnvl arger ars are shafts ior'driving sajidtractionwheels employed the.gears "of jonejt'rain; may oveili'e the in ol'iposit'e directions, saidtrans-mission me ns gears-or thecf'onipanioh train including two geartrains, one of which is enclosed "ch Hous ngs; the axis (if-c ne geareach of sa1d-tfaiiis being"{eoihcidentfwith the s' abUi-It which i-tshoii's'ifig pivots. stresses aria wearmg. 'Ihisis ds ihlebecausfe-dffaster-fir v h a'd ar rsysthe. 'closef'spa'c'in'g of the driving wheels,which ihchid ihgairaiii 'jsupjpo iii r 'W e S ib ire only the thickness'o'f fth w p rfi, sneer g aie caii-rid ws'aiwmine a'rid which ride-upontl 'l e'close spacing of thesju'pportingwhee'l s which "3) -"a'fi'ge aiaiii'qf sueh a s ystem, cooperating are slfiaceolv inwardlyfrom theed'gs'd f thelower traction wheels which 'frictibhallir engageoppofi'aii'ge'and'canmove freely1atera11y,'within'1imits, site side'so'f-saic'i -1'1- the-ax'e srssia traction dhfsjaidflange. Thestippo'rting wheels thus 'c aifry wheelsbeih normal to the a'ices'ofsaid supp'oi t- 'oniyfthe weight of thetractor and 'do not have 2,; ingwheel's, housings 'pivotallymounted on'said to guide the latter, one endof the {tractor being 'rramebe ow said-'i'aihs'hafts eit-tendingnpwardlyguided bythe 'horizontallysuppdrted wheels c'la'rtram said housings ier"carrying said traction 'i 'ied by the'trolley l8 whileth'e opposite endis wheel'sg a mofiorjafid transmission "means -includguided by the drivewheels fisiahd ii qwhicl also ihg "two ge'artrai'rfs for connecting saidmotor to tabili 3 r s pr i co nt r ctj' ny nde c 30 smash its iar'd'rii/inig saideaction wheel s -in Qf th atter tosw'a'y. jhe us'e qt apair Of drivoppd'si-eaireetibrisgne of-said'geartrains-being i' e fil aner d s ibed l qhashth e'nciosea in eah or said h'ousiri'g's 'and thegea'rs i i f at Wearing n destruction if-(me train being-nemesis adifierent plane than the gears of the other, whereby the gears esin'rithofit slilijectin the rail to; severe 6 t i s f. h i ie W eels r'll pbs e t i 'ti'res-on thewheels is rednced t o a 'mini i ift 3. 'O'f-Ohe train iriay '(W'eflie, or he moved to posi qr Pfi in fi 1 9 We???assess. .8? bei trons m which theyoverlie', the gears ofthecom- Tsi j ftg ig iy nfi i e f i 9; gI?PPPdH} i 9 -pa'nion train withoutinterferenc'e between' the w m. o TCL-Y l ,avmga'slng e W 69 gElEZ-IS 0fthe 313W) 'filtl'ns. d w ld' WWWFQQ s; A ihonoraiil ftractor foroverheadcarrier*sys- T H i a. I aredairid b" said-frame arid 'which'ride u on sincluding supporting, w l f m h id 99 a flange of a rail bf su'chasystem, cooperai ng a rail Such STYS'tEmQtZOPPOSitQSidQS tractionwheelswhich frictionally engage oppoa vertical the ewmmfihg'tmctidn sitesides of said-"rail the axes of said traction Wheels having bomp issiblefiifis Whidh "engage 45. i m- 0 vsai su opposite sides oflsaidweb theaxes'o isaidtraction g 3135 55 325;ig g fi i g t fi hi -P f 5 9???? fi iframe below said rail, shaftsextendingupwardly r t V i .-ensn1uining'aga'inst saidhousings for causing said traction i t Y h 1 wheels toengage said webwi'th a predetermined p for.dnvmg a e i W s oppopiessur'e 'a motor and transmi sion ineans conslte dlrectlons one 9 geartrams i 'i necting saidmo-tor arid said'sh'aft'sifor'driving. said 9 5i;z gfi :2tg fi ifpi g gi hiii zis traction wheels in opposite'directionsto-propel a p 7 said tractor along said rail, said. transmission h? i fim whereby the meansvincluding 't'wo gear trains,ene for driving m may(New? ,Y? each shaft and .ach of which is enclosed mom of W i wf e gearsI 8 common Said housings tra n without interference between the-gears of2. Amonor'ail tractor foroverheadcarriersysh two r m m adlustmg-the-te'ms;inc1uding-a frame, supporting wheels. which 011s W mg i gYgsubstntlany are'car'riedby said frame and which ride upon aeflual'degree thep'ressure 'Wlth f fia trac" flange of a rail of such asystem, cooperating trac- 'tmnwheels caused toiengage Wheels whichfrictionmEF-en-gage ijo it 6. -A-monora11.tractorfor overheadcarner sys-'sidesnofsaid rail, tha -axes of saiditraction wheels h ludinga frama.ppor n wh w i h 'being normal to the axes of "said supporting carried Y'f d' vWhichfide p Wheels, housingsipivotally-inountedon said frame flaqfa a l'qi such asystem; cooperating t rail, shafts which extend uwardly traction wheelswhichfrlctlonally engage oppofrom saidhousingsfifor carrying said traction e d s of Said fail, the axes ofsaid traction wheels, amotor, and transmission means connect-Wheelsrbeing f l tofhe'axes 0f D P- in said motor to said shafts fordrivin s'aid tracs W l p smg p t y unt d-on said tion wheels in Oppositedirections, said tran'smisframe 'b w d Trail, S ts e te d g'upwardlysion meansincludi'rig'two gear trains, one of'which from said housings'for carry n s'aid 'tra'ction islenclosed in eachiof said housings.Wheels, a;motor, transmission means'conne'cting 35A monorail tractor foroverhead'carrier 'sys- 7 saidfmotorzto said shafts fordrivihgsaidtraction wheels in opposite directions said transmission means includingtwo gear trains, one of. which is carried by each of said housings andeach of which includes an idler gear and a shaft on which said gearmounted, the axis of a one gear of each of said trains being coincidentwith the axis about which its housing pivots, means for mounting theshafts of said idler gears in various positions along the lines of theaxes of the gears of said trains in order to'enable the use of gears ofdifferent ratios in said trains and means for adjusting said housings toobtain the desired traction between said traction wheels and said rail.'7. A monorail tractor for overhead carrier sysmal to the axes of saidtraction wheels, and

transmission means connecting said motor to said shafts for driving saidtraction wheels in opposite directions, said transmission meansincluding two gear trains, one of which is enclosed in each of saidhousings, and a vertical drive shaft.

, 8. A monorail tractor for overhead carrier sys-' tems including asupporting frame, trolleys for suspending the front and rear ends ofsaid frame below said rail, said trolleys having wheels which ride upona horizontal flange of a rail of such a system between the marginaledges of said flange and a vertical web of the rail, cooperatingtraction wheels which frictionally engage opposite sides of said web,the axes of said traction wheels being normal to the axes of saidsupporting wheels, housings pivotally mounted on said frame below'saidrail, shafts extending upwardly from said housings for carrying saidtraction wheels, a motor, and transmission means connecting said motorto said shafts for'driving said traction wheels in opposite directions,said transmission means including two gear trains, one of which iscarried by each of said housings.

9. A monorail tractor for overhead carrier systems including a frame,supportingiwheels which are carried by said frame and which ride upon aflange of a rail of such a system, cooperating traction wheels whichfrictionally engage opposite sides of said rail, the axes of saidtraction wheels being normal tothe axes of said supporting wheels,housings pivotallymounted on said frame below said rail, shaftsextending upwardly from said housings for carrying said traction wheels,a motor, transmission means connecting said motor to said shafts fordriving said traction wheels in opposite directions, said transmissionmeans including two gear trains, one of which is carried by each of saidhousings, the axis of one gear of each of said trains being coincidentwith the axis about which its housing pivots, and means for adjustingthe positions of said housings to cause said traction wheels to engagesaid rail with the desired pressure.

10. A monorail tractor for .overhead carrier systems including a frame,flangeless, load-supporting wheels for said frame which ride uponjaflange of a rail of such a system at opposite sides of a vertical webof said rail, cooperating traction wheels which engage'opposite sides ofsaid rail, the axes of said traction wheels being normal to the axes ofsaid load-supporting wheels, supports for said traction wheels carriedby'said frame and mounted for adjustable movement in a lateral directionwith respect to said frame,a motor connected to said traction wheels fordrivingv said tractor along said rail, said traction wheels also servingto guide a pair of said load-supporting wheels so that they traversepredetermined paths along said flange, and means for causing saidtraction wheels to engage said fail with a predetermined pressure. v

I 11. A monorail tractor for overhead carrier systems including a frame,two pairs of flangeless, load-supporting wheels which ride upon a flangeof. a rail of such a system at opposite sides of a vertical web of saidrail and from which said frame is suspended, a swiveled trolleysuspended from one pair of said wheels, companion pairs of guide rollerswhich are carried by said trolley and which engage opposite sides ofsaidrail to guide said last mentioned pair of load-supporting wheels alongsaid flange, cooperating traction wheels which engage opposite sides ofsaid rail, the axes of said traction wheels being normal to the axes ofsaid load-supporting wheels, supports for said traction wheels carriedby said frame and mounted for adjustable movement in a lateral directionwith respect to said frame, a motor connected to said traction wheelsfordriving said tractor along said rail, said traction wheels serving toguide the other pair of saidv load-supporting wheels so that theytraverse predetermined paths along said flange, and means, whereby saidtraction wheels may be caused to engage said rail with a predeterminedpressure.

12. A monorail tractor for overhead carrier systems including a frame,flangeless, load-supporting wheels which ride upon a flange of a rail ofsuch a system at opposite sides of a vertical web of said rail and fromwhich said frame is suspended, cooperating traction wheels which engageopposite sides of said rail, the axes of said traction wheels beingnormal to the axes of said load-supporting wheels, housings pivotallymounted on said frame below said rail, shafts extending upwardly fromsaid housings for carrying said traction wheels, a motor for drivingsaid tractor along said rail, said traction wheels also serving to guidea pair of said load-supporting wheels so that they traversepredetermined paths along said flange, and transmission means connectingsaid motor to said shafts, said transmission means including two geartrains, one of which is enclosed in each of said housings, the axis ofthe leading gear of each gear train being coincident with the axis aboutwhich the housing for said gear train pivots.

13. A monorail tractor for overhead carrier systems including a frame,two pairs of flangeless, load-supporting wheels which ride upon a flangeof a rail of such a system at opposite sides of a vertical web of saidrail and from which saidframe is suspended, a swiveled trolley suspendedfrom one pair of said wheels, companion pairs of guide rollers which arecarried by said trolley and which engage opposite sides of said rail toguide said last mentioned pair of loadsupporting wheels along saidflange, cooperating traction wheels which engage opposite sides of saidrail, the axes of said traction wheels being normal to the axes of saidload-supporting wheels, housings pivotally mounted at their inner endsin said frame below said rail, shafts extending upwardly from saidhousings for carrying said traction wheels, means for adjusting theouter ends of said housing to cause said traction wheels to engage saidrail with a predetermined pressure, a motor for driving said tractoralong said rail, said traction wheels also serving to guide the otherpair of said load-supporting wheels so that they traverse predeterminedpaths along said flange, and transmission means connecting said motor tosaid shafts, said transmission means including two gear trains, one ofwhich is enclosed in each of said housings, the

I axis of the leading gear of each gear train being coincident with theaxis about which the housing for said gear train pivots.

14. A monorail tractor for overhead carrier systems including a frame,load-supporting wheels which ride upon a flange of a rail of such asystem at opposite sides of a vertical web of said rail and from whichthe opposite ends of said frame are suspended, cooperating tractionwheels which engage opposite sides of said rail, the axes of saidtraction wheels being normal to the axes of said load-supporting wheels,a motor mounted on the under side of said frame and connected to saidtraction wheels for driving said tractor along said rail, companionhousings pivotally mounted at their inner ends upon the upper side ofsaid frame below said rail, transmission means connecting said motor tosaid traction wheels, said transmission means including two gear trains,one of which is enclosed in each of said housings, the axis of the innergear of each gear train being coincident with the axis about which thehousing for said gear train pivots, a vertical shaft driven by the outergear of each of said gear trains, said shafts extending upwardly atopposite sides of said rail and carrying said traction wheels, and meansacting against said housings for causing said,

traction wheels to engage said rail with a predetermined pressure.

15. A monorail tractor for overhead carrier systems including a frame,trolleys for suspending the front and rear ends of said frame below arail of said system, said trolleys having flangeless wheels which rideupon a flange of said rail at opposite sides of a vertical web thereof,cooperating traction wheels, supports for said traction wheels carriedby said frame and mounted for adjustable movement in a lateral directionwith respect to said frame, means on said frame for acting upon saidsupports to cause the traction wheels to engage frictionally oppositesides of said web, the axes of said traction wheels being normal to theaxes of said supporting wheels, a motor mounted on said frame andgearing operatively connecting said motor and said traction wheels.

16. A monorail tractor for overhead carrier systems including a frame,trolleys for suspending the front and rear ends of said frame below arail of said system, said trolleys having flangeless wheels which rideupon a flange of said rail at opposite sides of a vertical web thereof,cooperating traction wheels, housings pivotally mounted on the upperside of said frame below said flange, shafts extending upwardly fromsaid housings for carrying said traction wheels, a motor mounted on theunder side of said frame, a gear train in each of said housingsconnecting said motor with one of said shafts, and means on said framefor acting against said housings to cause said traction wheels to engagefrictionally the opposite sides of said web, the axis about which eachof said housings may pivot in response to said last-mentioned meansbeing coincident with the axis of one of the gears in the train withwhich the housing is associated.

17. A monorail tractor for overhead carrier systems including a frame,trolleys for suspending the front and rear ends bf said frame below arail of said system, said trolleys having flangeless wheels which rideupon a flange of said rail at opposite sides of a vertical web thereof,co-

.operating traction wheels, housings pivotally mounted on the upper sideof said frame below said flange, drive shafts for said wheels carried byand extending upwardly from said housings, outboard bearings for theupper ends of said shafts, brackets which are mounted on said hous ingsand which carry said bearings, a motor mounted on the under side of saidframe, a gear train in each of said housings connecting said motor withone of said shafts, and means on said frame for acting against saidhousings to cause said tractionwheels to engage frictionally theopposite sides of said web, the axis about which each of said housingsmay pivot in response to said last mentioned means being coincident withthe axis of one of the gears in the train with which the housing isassociated.

18. A monorail tractor for overhead carrier systems including a frame,trolleys for suspending the front and rear ends of said frame below arail of said system, said trolleys having flange-- less wheels whichride upon a flange of said rail at opposite sides of a vertical webthereof, the front trolley having a swivel mounting about a verticalaxis, companion pairs of guide rollers carried by said front trolley andengaging opposite sides of said rail to guide the front pair ofload-supporting wheels along the flange of the rail, cooperatingtraction wheels, supports for said traction wheels carried by said,frame and mounted for adjustable movement in a lateral direction withrespect to said frame, means for acting upon said supports to cause thetraction wheels to engage frictionally opposite sides of said web, theaxes of said traction wheels being normal to the axes of said supportingwheels, said traction wheels also serving to guide the rear pair ofloadsupporting wheels along said flange, a motor mounted on said frameand gearing operatively connecting said motor and said traction wheels.

GEORGE F. GOGA.

